What could go wrong with the Transportation Security Administration’s (TSA) plan to allow small knives and some sports equipment back on airplanes for the first time since 9/11?

A lot.

Carry-on Confusion

TSA has decided small knives less than 2.36 inches long and no wider than half an inch as well as sports equipment such as hockey and lacrosse sticks, billiard cues, ski poles, souvenir-sized bats and up to two golf clubs per person “are unlikely to result in catastrophic destruction of an aircraft.”

But some larger items, such as hockey sticks, may still not make it onto airplanes because “airline policy dictates what can or cannot be stored in the overhead bins and under the seats,” said TSA spokesperson David Castelveter.

United Airlines and Southwest Airlines spokespeople told me that their current carry-on policies will apply after April 25, when the new rules are set to go into effect. But American Airlines Matt Miller said that airline is reviewing their policies and may update them, “as necessary.”

Bottom line: After April 25, be sure to check your airline’s carry-on rules before you fly.

State vs. Federal Rules

The new TSA rules will allow small knives to pass through the security checkpoint as a carry-on item, but Michigan put a law on its books after 9/11 prohibiting all knives (as well as firearms, explosives, razors and box cutters) in secure areas of airports.

The Michigan attorney general insists that this law will remain in place.

The TSA agrees. “It remains the responsibility of passengers to comply with state and local laws for each point of travel and be aware that origination and destination cities may have local laws prohibiting the possession of these items,” said TSA’s Castelveter.

Detroit Metropolitan Airport spokesperson Scott Wintner said Airport Authority Police officers will enforce the Michigan law “when violations come to their attention,” but aviation attorney Adam Wasch, with Wicker Smith in Fort Lauderdale, FL said “the courts may eventually decide that TSA rules pre-empt state rules on these matters.”

In the meantime, “allowing two sets of conflicting policies on whether pocket knives are prohibited muddies the water for passengers and creates a logistical nightmare for TSA workers.”

Piles of petitions

Unions and associations representing many flight attendants, federal air marshals and pilots are actively opposing the impending TSA rule changes.

The Flight Attendants Union Coalition has begun a campaign to reverse the TSA rules and on Saturday morning had about 15,000 signatures on a White House petition

The White House is required to respond if a petition gets at least 100,000 signatures.

The Federal Law Enforcement Officers Association (FLEOA), which represents air marshals has issued its own statement opposing what it calls “TSA’s reckless knife carry-on policy.”

At least one airline has officially come out against the TSA’s new rules.

On Friday, Delta Air Lines chief executive officer Richard Anderson sent a letter to TSA chief John Pistole voicing objection “to the agency decision to allow small knives back in the aircraft cabin.”

Anderson said the airline shared the flight attendant group’s “legitimate concerns” about the decision and said “If the purpose is to increase security checkpoint flow, there are much more effective steps we can take together to streamline the security checkpoints with risk-based screening mechanisms.”

29 year-old Ian Funderburg, who has been a flight attendant with a major domestic airline for the past two years, is also speaking out against TSA’s new rules.

“Baffled” to learn that knives would soon be allowed back on-board airplanes, Funderburg started his own campaign on the popular petition platform Change.org.

On Saturday morning Funderburg’s petition currently has more than 8,000 signatures.
“It’s not just a fear for flight attendants. The rules will probably renew fear in passengers,” said Funderburg. “We have to stop it.”

( This is a slightly updated version of my story about the TSA’s new rules that appeared on NBC NEWS.)